Diaphragm pump



DIAPHRAGM PUMP Filed Feb. 14, 1956 lNVEN TO R' W 2 BY ATTO R N EY5United States Patent 2,861,518 DIAPHRAGM PUMP Friedrich Wilhelm Pleuger,Hamburg, Germany Application February 14, 1956, Serial No. 565,465Claims priority, application Germany February 17, 1955 8 Claims. (Cl.103-44) This invention relates to submersible pumps for deep. wellpumping, and more particularly, to a diaphragm pump for submersion in anoil well in order to pump from great depths.

In petroleum drilling it is often necessary to pump 01f brine lyingunderneath the petroleum deposit before commencing the pumping of theoil itself. In such operations it is not uncommon to encounter pressuresat the bottom of the oil deposit of the order of several hundredatmospheres. When it is attempted to operate a pump under such highpressures, leakage problems are encountered with respect to the pumppacking.

The invention provides for minimizing such leakage problems byequalization of the pressure inside and out side of the pump. Briefly,the invention involves the provision of a plurality of pistons operatingthrough sealed hydraulic pressure chambers on flexible diaphragms whichare exposed to an act upon oil in pumping chambers. In the preferredform of the invention the pistons are provided in paired opposingrelation and operate within a liquid-filled pressure compensationchamber.

The primary object of the invention is the provision of a diaphragm pumpcapable of sustained operation even when submerged to the bottom of theoil deposit in an oil well.

A further object of the invention is the provision in a diaphragm pumpof a hydraulic pressure transfer chamber (adapted to exert the forcegenerated by a reciprocating piston on a flexible diaphragm) and anassociated liquid-filled pressure compensation chamber whereby thepressure of oil from the surrounding strata is balanced by the pressureof the incompressible liquid within the pumping unit.

Still further, the invention has as an object the provision of a pumpwhich can be used during prolonged operation at various temperatures,the object here in question being to provide automatic compensation forexpansions and contractions of the volume of the pressure liquidresulting from fluctuations in temperature.

Yet another object of the invention is the provision, in a diaphragmpump having a plurality of pistons acting to distort flexiblediaphragms, of means for automatically compensating for liquid whichleaks out of the pressure transfer chambers between the pistons andcylinder wall How the foregoing and other objects and advantages of theinvention are attained will appear more clearly from the followingdescription, taken together with the accompanying drawing showing avertical section of a diaphragm pump according to the invention.

An electric motor, preferably of the squirrel cage type, is mountedwithin the tubular housing 1, the rotor thereof being schematicallyshown at 2. The motor shaft 3, conveniently arranged concentrically ofthe pump housing 1, is journalled at its free end in the ball bearing 4.An eccentric or cam 6 (together with a surrounding needle bearing ismounted on the motor shaft 3 and drives a yoke or other similar memberinterconnecting the pistons 7-7 for conjoint reciprocation.

While the drawing illustrates an embodiment having two radially alignedand opposed pistons, it is contemplated that any convenient number ofpistons may be used, the preferred forming involving an even number ofpistons arranged in opposed pairs and generally radially disposed aroundthe eccentric.

Piston rings 8 are provided on the pistons 7 and 7' to minimize leakageof pressure liquid between the pistons and cylinder walls. The cylindersare preferably formed as bores in a common cylinder housing 9. Theportions of the cylinders ahead of the pistons provide working spaces 10and 10 which may be sealed by means of removable plugs 11.

The working spaces 10 and 10 of the pistons are in communication, viathe passageways 12 and 12' with pressure chambers 13 and 13',respectively.

Flexible diaphragms 14 and 14 separate the pressure chambers 13 and 13from the pumping chambers 15 and 15, respectively. The pressure chambers13 and 13', the passageways 12 and 12, and the cylinders in which thepistons 7 and 7 act are all filled with gas-free pressure liquid.

The pumping chambers 15 and 15' are adapted to draw from the wellthrough inlet passages 23 and 23' provided with one-way inlet valves 16and 16, and to deliver to the well riser 18 via one-way outlet valvemeans 17 and 17'.

The piston and cylinder devices with their associatedparts (the pressurechambers 13 and 13, pumping chambers 15 and 15', diaphragms 14 and 14,passageways 12 and 12', working spaces 10 and 10', etc.) are arrangedsymmetrically with reference to a plane containing the vertical axis ofthe housing.

The space surrounding the motor, eccentric, yolk, pistons and bearingsforms a liquid-filled pressure compensation chamber 19 within thehousing 1.

In order to compensate for liquid which leaks past the pistons from theworking spaces 10 and 10 into the compensation chamber 19, ducts 20 and20' are provided through the bottom wall of the cylinder housing 9.Spring loaded non-return valves 21 and 21' are arranged in the ducts 20and 20 respectively, so as to prevent escape of liquid from the spaces10 and 10 and to permit flow of liquid from the compensation chamberinto the spaces when the leakage past the pistons has reduced the volumeof liquid in the system to the point where sufficient suction is builtup during the suction stroke of the piston to overcome the seating forceof the valve springs. Thus, there is provided a communication betweenthe pressure compensation chamber 19 and the pressure chambers 13 and 13through non-return valve means.

In order to insure an additional pressure compensation of thecompensation chamber 19 with the outside pressure, and also for thecompensation of possible volume displacements resulting from the pistonmovements,

the external flexible diaphragm 22 may be disposed in the housingwall 1. The external diaphragm or compensation diaphragm 22 may bearranged at any convenient place in the housing, the drawing showing itin the side wall near the top of the motor. However, it is also possibleto arrange the diaphragm 22 below the motor in the bottom cap (notshown) of the housing 1.

According to one aspect of the invention, the external diaphragm 22 mayeven be eliminated, that is, when the pistons are arranged so as toavoid displacement of any appreciable volume of the liquid in thecompensation chamber during a cycle of the pistons. In other words, whenone piston extends into the compensation chamber, the other piston willbe advanced into its cylinder and vice versa. Thus, the actual volume ofthe compensation chamber remain-s substantially constant. With such anarrangement the external diaphragm 22 may not be necessary.

Patented Nov. 25, 1958 v The embodiment of the invention shown in thedrawings operates in the following manner:

After the electric motor has been connected with the power supply line,the rotor 2 rotates in the compensation chamber 19 and imparts to thedouble piston arrangement 7-7 a reciprocating movement by means of theeccentric 6 and the yoke interconnecting the pistons. Since the twopistons are of the same shape and size, their displacements-are equaland the backward and forward movement causes no change of volume in thepump housing.

The pressure liquid within the passageways and pressure chambers flows,in response to motion of the pistons, alternately through thepassageways 12 and 12 and into the pressure chambers 13 and 13', thusalternately distending and relaxing the diaphragms 14 and 14'. Theperiodic changing of the volume of the pressure chambers 13 and 13correspondingly increases and decreases the volume of the workingchambers 15 and 15. The change in volume of the working chambers effectsan alternate intake of oil through passage 23 or 23' and check valve 16or 16' and an outflow of oil through outlet valve 17 or 17' and into thewell riser 18.

Pressure liquid which leaks between the pistons and cylinder wallsduring operation is automatically compensated for on each piston strokein the suction direction by intake of pressure liquid from thecompensation chamber through the passages 20 or Ztl and spring loadednonreturn valves 21 or 21. If the volume of the liquid in the pressurechambers and connected spaces increases due to a rise in temperature,the diaphragms 14 and 14' will bulge slightly and assume a newequilibrium position. The pressure inside and outside the pump isthereby maintained in balance and no excessive strain is placed on anypackings involved. w

Thus, even if the volume of the liquid in the pressure chamberincreases, the pump operation continues unimpaired because of thedistention of the diaphragms 14 and 14' to a new neutral position. Ifthe temperature subsequently drops to normal operating temperature, thediaphragms 14 and 14 will again assume their original neutral position.

While various arrangements of the parts of the invention are possible,it is preferred to arrange the diaphragms generally vertically Withinthe housing and to arrange the pistons generally radially in horizontalposition below the diaphragms. Such an arrangement of the pistonsfacilitates a rotating cam or eccentric drive of the kind shown and alsoinsures that the lengths of the passageways from the cylinders to therespective pressure chambers will all be substantially equal andtherefore have substantially equal pressure drops. The radial typearrangement in efiect provides for driving of the pistons in phaseopposition and for symmetrical arrangement of the parts.

As will be seen from the drawing, the structure of the pump according tothe invention is arranged in several major sections which are mountedone on top of another axially. Thus, the bottom section or portionhouses the electric motor, the next section contains the piston andcylinder devices, the next the pumping chambers and pressure chambers,the next the pressure outlet valves and finally the connection with thepump riser or delivery pipe. This structural arrangement makes for readyassembly and also for ease of replacement and repair of various parts ofthe invention, without a complete disassembly.

I claim:

1. For the withdrawal of liquids upwardly through the riser of a deepwell, a pump submerged in the liquid, said pump comprising, a pluralityof piston and cylinder devices each in communication with a pressurechamber, pressure transfer liquid filling the cylinders and pressurechambers, a pumping chamber adjacent-each pressure chamber, a flexiblediaphragm separating each pressure chamber from the adjacent pumpingchamber, each pumping chamber being adapted to draw from the wellthrough first passage means and deliver to the well riser through secondpassage means, one-way inlet valve means in said first passage means andone-way outlet valve means in said second passage means, means fordriving the pistons, a liquidfilled compensation chamber, the open endsof said cylinders being in communication with the compensation chamber,and a flexible compensation diaphragm in the wall of the compensationchamber, said compensation diaphragm being exposed to the pressure inthe well outside the pump on one side and to the pressure of the liquidin the compensation chamber on the other side.

2. A deep well pump according to claim 1 in which the liquid filledcompensation chamber is in communication with each of said pressurechambers via conduit means, and in which non-return valve means areprovided in said conduit means to prevent flow into the compensationchamber. i

3. A pump according to claim 1 in which the means for driving thepistons is located Within the compensation chamber, and in which each ofthe piston and cylinder devices is paired with an opposing device,whereby the volume of the compensation chamber remains substantiallyconstant.

-4. A pump according to claim 1 in which the cylinders are arranged in acommon cylinder housing.

5. A pump according to claim 1 in which the pressure chambers andpumping chambers are arranged above the piston and cylinder devices andthe means for driving saiddevices.

6. Aconstruction according to claim 2 in which the non-return valvemeans are spring-loaded.

7. For the withdrawal of liquids upwardly through the riser of a deepwell, a pump submerged in the liquid, said pump comprising, a pumphousing, a plurality of pumping chambers within said housing, eachpumping chamber'being adapted to draw from the well through firstpassage means and deliver to the well riser through second passagemeans, one-Way inlet valve means in said first passage means and one-wayoutlet valve means in said second passage means, a pressure chamberopposed to each pumpingchamber, a flexible diaphragm separating eachpressure chamber from its pumping chamber, said diaphragms beinggenerally vertically disposed within said housing, a generallyhorizontally disposed piston and cylinder device for each pressurechamber, a passageway connecting each cylinder with its pressurechamber, pressure transfer liquid filling the cylinders, passageways andpressure chambers, a liquid-filled compensation chamber,. means withinthe compensation chamber for driving the pistons in phase opposition,the open ends of the cylinders being in communication with thecompensation chamber, and a flexible compensation diaphragm in the wallof the compensation chamber, said compensation diaphragm being exposedto the pressure in the well outside the pump on one side and to thepressure of the liquid in the compensation chamber on the other side.

8. For the withdrawal of liquids upwardly through the riser of a deepwell, a pump submerged in the liquid, said pump comprising a housinghaving a generally vertical axis, a pair of piston and cylinder deviceseach in communication with a pressure chamber, a pumping chamber opposedto each pressure chamber, a flexible diaphragm separating each pressurechamber from its pumping chamber, said piston and cylinder devices andpumping and pressure chambers being arranged symmetrically withreference to a plane containing said axis of the housing, pressuretransfer liquid filling the cylinders and pressure chambers, the pumpingchambers being adapted to draw from the well and deliver to the wellriser, a liquid-filled compensation chamber, means within thecompensation chamber for driving the pistons in phase opposition, theopen ends of the cylinders being in communication with the compensationchamber, and a flexible compensation References Cited in the file ofthis patent diaphragm in the wall of the compensation chamber, saidcompensation diaphragm being exposed to the pressure in UNITED STATESPATENTS the Well outside the pump on one side and to the pressure1,301,485 Mueller Apr. 22, 1919 of the liquid in the compensationchamber on the other 5 1,851,666 Evans Mar. 29, 1932 side. 2,343,962Dodson Mar. 14, 1944

